The present invention relates to a toroidal core for a toroid
Toroids are commonly used as current transformers or couplers in electrical equipment or devices such as an earth fault circuit breaker. Over-magnetization leading to saturation of the core of a toroid is undesirable, as this may lead to improper operation and/or overheating.
The subject invention seeks to mitigate or at least alleviate such a problem by providing an improved toroidal core for a toroid.
According to the invention, there is provided a toroidal core for a toroid, comprising at least two toroidal rings that are stacked co-axially one upon another. At least a first of said at least two toroidal rings has a body including a gap forming a break in one side of the body.
Preferably, the gap extends substantially radially with respect to the body of the first ring.
It is preferred that the gap has a substantially uniform width.
Preferably, the gap is formed at the same time as the body of the first ring is moulded into shape.
It is preferred that the gap is filled up by a non-ferromagnetic filler.
It is further preferred that the filler has an outer surf ace which lies flush with that of the parts of the body of the first ring forming the gap.
It is yet further preferred, that the body of the first ring and the filler are completely covered by an insulating coating.
Preferably, said at least two toroidal rings have respective bodies which have substantially the same outer and inner diameters as one another.
In a first preferred embodiment, the toroidal core includes only two said toroidal rings including one said first toroidal ring.
In a second preferred embodiment, the toroidal core includes at least three said toroidal rings, wherein the first ring is an intermediate ring in the stack.
The invention also provides a toroid incorporating the aforesaid toroidal core, in which the toroid includes at least one winding wound on the toroidal core, whereby said at least two toroidal rings are secured together.